Substituted aminoxy succinate stabilizer for polymers

ABSTRACT

Substituted aminoxy succinate derivatives of the formula ##STR1## are effective in stabilizing organic materials against oxidative, thermal and actinic degradation, said derivatives being particularly effective as color improvers and process stabilizers in organic materials containing phenolic antioxidants and/or metal salts of fatty acids and/or hindered amine light stabilizers and/or organic phosphorus compounds.

Organic polymeric materials such as plastics and resins are subject tothermal, oxidative and photodegradation. A great variety of stabilizersare known in the art for stabilizing a diversity of substrates. Theireffectiveness varies depending upon the causes of degradation and thesubstrate stabilized. In general, it is difficult to predict whichstabilizer will be most effective and most economical for any one areaof application. For example, stabilizer effectiveness in reducingvolatility may depend upon preventing bond scission in the substratemolecule. Limiting embrittlement and retaining elasticity in a polymeror rubber may require prevention of excessive crosslinking and/or chainscission. Prevention of discoloration may require inhibiting reactionswhich yield new chromophores or color bodies in the substrate orstabilizer. Problems of process stability and incompatibility must alsobe considered.

Various organic hydroxylamine compounds are generally known and some arecommercially available. A number of patents disclosenitrogen-substituted hydroxylamines as antioxidant stabilizers forvarious substrates including polyolefins, polyesters and polyurethanes.U.S. Pat. Nos. 3,432,578, 3,644,278, 3,778,464, 3,408,422, 3,926,909,4,316,996, 4,386,224 and 4,590,231 are representative of such patentswhich basically disclose N,N-dialkyl-, N,N-diaryl and N,N-diaralkylhydroxylamine compounds and their color improvement and colorstabilizing activity.

It has now been determined that the compounds of this invention exhibita variety of desirable properties which makes them particularlyeffective and useful as stabilizers. Thus, the compounds serve toprotect various substrates such as polyolefins, elastomers andlubricating oils against the adverse effects of oxidative and thermaldegradation. They are most effective as color improvers and processstabilizers in polyolefin compositions which may contain metal salts offatty acids and which also contain a phenolic antioxidant. Thus, theyserve to substantially reduce color formation resulting from thepresence of the phenolic antioxidant and/or from the processingconditions as well as to directly protect the polymer from saidprocessing conditions. They also prevent the discoloration of polyolefincompositions containing hindered amine light stabilizers or combinationsof phenolic antioxidants and organic phosphites. In addition, the gasfading that may be experienced upon exposure to the combustion productsof natural gas is also significantly reduced.

It is the primary object of this invention to provide a class of novelsuccinate derivatives which exhibits a broad range of improvedstabilization performance characteristics.

It is a further object to provide compositions of organic materialsstabilized against oxidative, thermal and actinic degradation by thepresence therein of said derivatives.

It is still a further object to provide such compositions which alsocontain phenolic antioxidants wherein said succinates substantiallyreduce color formation resulting from the presence of said phenols.

Various other objects and advantages of this invention will becomeevident from the following description thereof.

The compounds of this invention correspond to the formula ##STR2##wherein R¹ and R² are independently alkyl of 1 to 36 carbon atoms,cycloalkyl of 5 to 12 carbon atoms, aralkyl of 7 to 9 carbon atoms orsaid aralkyl substituted by alkyl of 1 to 36 carbon atoms; and

R³ and R⁴ are independently hydrogen, an alkali metal, alkyl of 1 to 36carbon atoms, phenyl or phenyl substituted by alkyl of 1 to 12 carbonatoms.

The R¹ and R² groups are preferably straight-chain or branched alkylwith 1 to 18 carbon atoms such as methyl, ethyl, n-propyl, n-butyl,tert-butyl, n-pentyl, n-octyl, 2-ethylhexyl, decyl, dodecyl andoctadecyl; cyclopentyl and cyclohexyl; and benzyl, α-methylbenzyl, andα,α-dimethylbenzyl and cumyl benzyl.

The R³ and R⁴ groups are preferably straight-chain or branched alkylwith 1 to 18 carbon atoms such as the substituents noted for the R¹ andR² groups.

The derivatives of this invention can be prepared by reacting theappropriatedly substituted hydroxylamine with an appropriatelysubstituted maleate in a solvent to yield the desired product. Thesolvent system is preferably a heterocyclic ether such astetrahydrofuran or a glycol ether such as diglyme. The reactiontemperature ranges from 60° to 170° C. The preferred method involvesconducting the reaction in the presence of a proton acceptor includingmetal hydrides such as sodium hydride, lithium hydride, calcium hydrideor potassium hydride; alkali and alkaline-earth metal hydroxides such assodium hydroxide or potassium hydroxide; or metal alkoxides such assodium methoxide, sodium ethoxide or potassium tert-butoxide. Thestarting materials needed to prepare the stabilizers of this inventionare items of commerce or can be prepared by known methods.

The compounds of the present invention are particularly effective instabilizing organic materials subject to oxidative, thermal and actinicdegradation, such as plastics, polymers and resins.

Substrates in which these compounds are particularly useful arepolyolefins such as polyethylene and polypropylene; polystyrene,including impact polystyrene, ABS resin, SBR, isoprene, as well asnatural rubber, polyesters including polyethylene terephthalate andpolybutylene terephthalate, including copolymers, and lubricating oilssuch as those derived from mineral oil.

In general polymers which can be stabilized include

1. Polymers of monoolefins and diolefins, for example polyethylene(which optionally can be crosslinked), polypropylene, polyisobutylene,polybutene-1, polymethylpentene-1, polyisoprene or polybutadiene, aswell as polymers of cycloolefins, for instance of cyclopentene ornorbornene.

2. Mixtures of the polymers mentioned under (1), for example mixtures ofpolypropylene with polyisobutylene.

3. Copolymers of monoolefins and diolefins with each other or with othervinyl monomers, such as, for example, ethylene/propylene,propylene/butene-1, propylene/isobutylene, ethylene/butene-1,propylene/butadiene, isobutylene/isoprene, ethylene/alkyl acrylates,ethylene/alkyl methacrylates, ethylene/vinyl acetate or ethylene/acrylicacid copolymers and their salts (ionomers) and terpolymers of ethylenewith propylene and a diene, such as hexadiene, dicyclopentadiene orethylidene-norbornene.

4. Polystyrene, poly-(p-methylstyrene).

5. Copolymers of styrene or methylstyrene with dienes or acrylicderivatives, such as, for example, styrene/butadiene,styrene/acrylonitrile, styrene/ethyl methacrylate,styrene/butadiene/ethyl acrylate, styrene/acrylonitrile/methyl acrylate;mixtures of high impact strength from styrene copolymers and anotherpolymer, such as, for example, from a polyacrylate, a diene polymer oran ethylene/propylene/diene terpolymer; and block polymers of styrene,such as, for example, styrene/butadiene/styrene,styrene/isoprene/styrene, styrene/ethylene/butylene/styrene orstyrene/ethylene/propylene/styrene.

6. Graft copolymers of styrene, such as, for example, styrene onpolybutadiene, styrene and acrylonitrile on polybutadiene, styrene andalkyl acrylates or methacrylates on polybutadiene, styrene andacrylonitrile on ethylene/propylene/diene terpolymers, styrene andacrylonitrile on polyacrylates or polymethacrylates, styrene andacrylonitrile on acrylate/butadiene copolymers, as well as mixturesthereof with the copolymers listed under (5), for instance the copolymermixtures known as ABS-, MBS-, ASA-or AES-polymers.

7. Halogen-containing polymers, such as polychloroprene, chlorinatedrubbers, chlorinated or sulfochlorinated polyethylene, epichlorohydrinhomo- and copolymers, polymers from halogen-containing vinyl compounds,as for example, polyvinylchloride, polyvinylidene chloride, polyvinylfluoride, polyvinylidene fluoride, as well as copolymers thereof, as forexample, vinyl chloride/vinylidene chloride, vinyl chloride/vinylacetate or vinylidene chloride/vinyl acetate copolymers.

8. Polymers which are derived from α,β-unsaturated acids and derivativesthereof, such as polyacrylates and polymethacrylates, polyacrylamide andpolyacrylonitrile.

9. Copolymers from the monomers mentioned under (8) with each other orwith other unsaturated monomers, such as, for instance,acrylonitrile/butadiene, acrylonitrile/alkyl acrylate,acrylonitrile/alkoxyalkyl acrylate or acrylonitrile/vinyl halogenidecopolymers or acrylonitrile/alkyl methacrylate/butadiene terpolymers.

10. Polymers which are derived from unsaturated alcohols and amines, oracyl derivatives thereof or acetals thereof, such as polyvinyl alcohol,polyvinyl acetate, polyvinyl stearate, polyvinyl benzoate, polyvinylmaleate, polyvinylbutyral, polyallyl phthalate or polyallyl-melamine.

11. Homopolymers and copolymers of cyclic ethers, such as polyalkyleneglycols, polyethylene oxide, polypropylene oxide or copolymers thereofwith bis-glycidyl ethers.

12. Polyacetals, such as polyoxymethylene and those polyoxymethyleneswhich contain ethylene oxide as comonomer.

13. Polyphenylene oxides and sulfides, and mixtures of polyphenyleneoxides with polystyrene.

14. Polyurethanes which are derived from polyethers, polyesters orpolybutadiens with terminal hydroxyl groups on the one side andaliphatic or aromatic polyisocyanates on the other side, as well asprecursors thereof (polyisocyanates, polyols or prepolymers).

15. Polyamides and copolyamides which are derived from diamines anddicarboxylic acids and/or from aminocarboxylic acids or thecorresponding lactams, such as polyamide 4, polyamide 6, polyamide 6/6,polyamide 6/10, polyamide 11, polyamide 12,poly-2,4,4-trimethylhexamethylene terephthalamide or poly-m-phenyleneisophthalamide, as well as copolymers thereof with polyethers, such asfor instance with polyethylene glycol, polypropylene glycol orpolytetramethylene glycols.

16. Polyureas, polyimides and polyamide-imides.

17. Polyesters which are derived from dicarboxylic acids and diolsand/or from hydroxycarboxylic acids or the corresponding lactones, suchas polyethylene terephthalate, polybutylene terephthalate,poly-1,4-dimethylol-cyclohexane terephthalate,poly-[2,2-(4-hydroxyphenyl)-propane] terephthalate andpolyhydroxybenzoates as well as block-copolyether-esters derived frompolyethers having hydroxyl end groups.

18. Polycarbonates.

19. Polysulfones, polyethersulfones and polyetherketones.

20. Crosslinked polymers which are derived from aldehydes on the onehand and phenols, ureas and melamines on the other hand, such asphenol/formaldehyde resins, urea/formaldehyde resins andmelamine/formaldehyde resins.

21. Drying and non-drying alkyd resins.

22. Unsaturated polyester resins which are derived from copolyesters ofsaturated and unsaturated dicarboxylic acids with polyhydric alcoholsand vinyl compounds as crosslinking agents, and also halogen-containingmodifications thereof of low flammability.

23. Thermosetting acrylic resins, derived from substituted acrylicesters, such as epoxy-acrylates, urethane-acrylates or polyesteracrylates.

24. Alkyd resins, polyester resins or acrylate resins in admixture withmelamine resins, urea resins, polyisocyanates or epoxide resins ascrosslinking agents.

25. Crosslinked epoxide resins which are derived from polyepoxides, forexample from bis-glycidyl ethers or from cycloaliphatic diepoxides.

26. Natural polymers, such as cellulose, rubber, gelatin and derivativesthereof which are chemically modified in a polymer homologous manner,such as cellulose acetates, cellulose propionates and cellulosebutyrates, or the cellulose ethers, such as methylcellulose.

27. Mixtures of polymers as mentioned above, for example PP/EPDM,Polyamide 6/EPDM or ABS, PVC/EVA, PVC/ABS, PVC/MBS, PC/ABS, PBTP/ABS.

28. Naturally occuring and synthetic organic materials which are puremonomeric compounds or mixtures of such compounds, for example mineraloils, animal and vegetable fats, oil and waxes, or oils, fats and waxesbased on synthetic esters (e.g. phthalates, adipates, phosphates ortrimellitates) and also mixtures of synthetic esters with mineral oilsin any weight ratios, which materials may be used as plasticizers forpolymers or as textile spinning oils, as well as aqueous emulsions ofsuch materials.

29. Aqueous emulsions of natural or synthetic rubber, e.g. natural latexor latices of carboxylated styrene/butadiene copolymers.

In general, the compounds of the present invention are employed in fromabout 0.01 to about 5% by weight of the stabilized composition, althoughthis will vary with the particular substrate and application. Anadvantageous range is from about 0.5 to about 2%, and especially 0.1 toabout 1%.

The stabilizers of the instant invention may readily be incorporatedinto the organic polymers by conventional techniques, at any convenientstage prior to the manufacture of shaped articles therefrom. Forexample, the stabilizer may be mixed with the polymer in dry powderform, or a suspension or emulsion of the stabilizer may be mixed with asolution, suspension, or emulsion of the polymer. The resultingstabilized polymer compositions of the invention may optionally alsocontain various conventional additives, such as the following.

1. Antioxidants

1.1. Alkylated monophenols, for example,

2,6-di-tert.butyl-4-methylphenol

2-tert.butyl-4,6-dimethylphenol

2,6-di-tert.butyl-4-ethylphenol

2,6-di-tert.butyl-4-n-butylphenol

2,6-di-tert.butyl-4-i-butylphenol

2,6-di-cyclopentyl-4-methylphenol

2-(α-methylcyclohexyl)-4,6-dimethylphenol

2,6-di-octadecyl-4-methylphenol

2,4,6-tri-cyclohexylphenol

2,6-di-tert.butyl-4-methoxymethylphenol

1.2. Alkylated hydroquinones, for example,

2,6-di-tert.butyl-4-methoxyphenol

2,5-di-tert.butyl-hydroquinone

2,5-di-tert.amyl-hydroquinone

2,6-diphenyl-4-octadecyloxyphenol

1.3. Hydroxylated thiodiphenyl ethers, for example

2,2'-thio-bis-(6-tert.butyl-4-methylphenol)

2,2'-thio-bis-(4-octylphenol)

4,4'-thio-bis-(6-tert.butyl-3-methylphenol)

4,4'-thio-bis-(6-tert.butyl-2-methylphenol)

1.4. Alkyliden-bishenols, for example,

2,2'-methylene-bis-(6-tert.butyl-4-methylphenol)

2,2'-methylene-bis-(6-tert.butyl-4-ethylphenol)

2,2'-methylene-bis-[4-methyl-6-(α-methylcyclohexyl)-phenol]

2,2'-methylene-bis-(4-methyl-6-cyclohexylphenol)

2,2'-methylene-bis-(6-nonyl-4-methylphenol)

2,2'-methylene-bis-[6-(α-methylbenzyl)-4-nonylphenol]

2,2'-methylene-bis-[6-(α,α-dimethylbenzyl)-4-nonylphenol]

2,2'-methylene-bis-(4,6-di-tert.butylphenol)

2,2'-ethylidene-bis-(4,6-di-tert.butylphenol)

2,2'-ethylidene-bis-(6-tert.butyl-4-isobutylphenol)

4,4'-methylene-bis-(2,6-di-tert.butylphenol)

4,4'-methylene-bis-(6-tert.butyl-2-methylphenol)

1,1-bis-(5-tert.butyl-4-hydroxy-2-methylphenyl-butane

2,6-di-(3-tert.butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol

1,1,3-tris-(5-tert.butyl-4-hydroxy-2-methylphenyl)-butane

1,1-bis-(5-tert.butyl-4-hydroxy-2-methylphenyl)-3-n-dodecylmercaptobutane

ethylenglycol-bis-[3,3-bis-(3'-tert.butyl-4'-hydroxyphenyl)-butyrate]

di-(3-tert.butyl-4-hydroxy-5-methylphenyl)-dicyclopentadiene

di-[2-(3'-tert.butyl-2'-hydroxy-5'-methyl-benzyl)-6-tert.butyl-4-methylphenyl]-terephthalate.

1.5. Benzyl compounds, for example,

1,3,5-tri-(3,5-di-tert.butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene-di-(3,5-di-tert.butyl-4-hydroxybenzyl)sulfide

3,5-di-tert.butyl-4-hydroxybenzyl-mercapto-acetic acid isooctyl ester

bis-(4-tert.butyl-3-hydroxy-2,6-dimethylbenzyl)dithiolterephthalate

1,3,5-tris-(3,5-di-tert.butyl-4-hydroxybenzyl)-isocyanurate

1,3,5-tris-(4-tert.butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate

3,5-di-tert.butyl-4-hydroxybenzyl-phosphoric acid-dioctadecyl ester

3,5-di-tert.butyl-4-hydroxybenzyl-phosphoric acid-monoethyl ester,calcium-salt

1.6. Acylaminophenols, for example,

4-hydroxy-lauric acid anilide

4-hydroxy-stearic acid anilide

2,4-bis-octylmercapto-6-(3,5-tert.butyl-4-hydroxyanilino)s-triazine

octyl-N-(3,5-di-tert.butyl-4-hydroxyphenyl)-carbamate

1.7. Esters of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid withmonohydric or polyhydric alcohols, for example,

    ______________________________________                                        methanol        diethyleneglycol                                              octadecanol     triethyleneglycol                                             1,6-hexanediol  pentaerythritol                                               neopentylglycol tris-hydroxyethyl isocyanurate                                thiodiethyleneglycol                                                                          di-hydroxyethyl oxalic acid                                                   diamide                                                       ______________________________________                                    

1.8. Esters of β-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acidwith monohydric or polyhydric alcohols, for example,

    ______________________________________                                        methanol        diethyleneglycol                                              octadecanol     triethyleneglycol                                             1,6-hexanediol  pentaerythritol                                               neopentylglycol tris-hydroxyethyl isocyanurate                                thiodiethyleneglycol                                                                          di-hydroxyethyl oxalic acid                                                   diamide                                                       ______________________________________                                    

1.9. Amides of β-(3,5-di-tert.butyl-4-hydroxyphenyl)propionic acid forexample,

N,N'-di-(3,5-di-tert.butyl-4-hydroxyphenylpropionyl)hexamethylenediamine

N,N'-di-(3,5-di-tert.butyl-4-hydroxyphenylpropionyl)trimethylenediamine

N,N'-di-(3,5-di-tert.butyl-4-hydroxyphenylpropionyl)hydrazine

2. UV absorbers and light stabilizers

2.1. 2-(2'-Hydroxyphenyl)-benzotriazoles, for example, the 5'-methyl-,3',5'-di-tert.butyl-, 5'-tert.butyl-, 5'-(1,1,3,3-tetramethylbutyl)-,5-chloro-3',5'-di-tert.butyl-, 5-chloro-3'-tert.butyl-5'-methyl-,3'-sec.butyl-5'-tert.butyl-, 4'-octoxy, 3',5'-di-tert.amyl-,3',5'-bis(α,α-dimethylbenzyl)-derivative.

2.2. 2-Hydroxy-benzophenones, for example, the 4-hydroxy-, 4-methoxy-,4-octoxy, 4-decyloxy-, 4-dodecyloxy-, 4-benzyloxy, 4,2',4'-trihydroxy-and 2'-hydroxy-4,4'-dimethoxy derivative.

2.3. Esters of optionally substituted benzoic acids for example, phenylsalicylate, 4-tert.butyl-phenylsalicylate, octylphenyl salicylate,dibenzoylresorcinol, bis-(4-tert.butylbenzoyl)-resorcinol,benzoylresorcinol, 3,5-di-tert.butyl-4-hydroxybenzoic acid2,4-di-tert.butyl-phenyl ester and 3,5-di-tert.-butyl-4-hydroxybenzoicacid hexadecyl ester.

2.4. Acrylates, for example, α-cyano-β,β-diphenylacrylic acid ethylester or isooctyl ester, α-carbomethoxy-cinnamic acid methyl ester,α-cyano-β-methyl-p-methoxy-cinnamic acid methyl ester or butyl ester,α-carbomethoxy-p-methoxycinnamic acid methyl ester,N-(β-carbomethoxy-β-cyanovinyl)-2-methyl-indoline.

2.5 Nickel compounds, for example, nickel complexes of2,2'-thio-bis-[4-(1,1,3,3-tetramethylbutyl)-phenol], such as the 1:1 or1:2 complex, optionally with additional ligands such as n-butylamine,triethanolamine or N-cyclohexyl-di-ethanolamine, nickeldibutyldithiocarbamate, nickel salts of4-hydroxy-3,5-di-tert.butylbenzylphosphonic acid monoalkyl esters, suchas of the methyl, ethyl or butyl ester, nickel complexes of ketoximessuch as of 2-hydroxy-4-methyl-phenyl undecyl ketoxime, nickel complexesof 1-phenyl-4-lauroyl-5-hydroxy-pyrazole, optionally with additionalligands.

2.6. Sterically hindered amines, for examplebis-(2,2,6,6-tetramethylpiperidyl)-sebacate,bis-(1,2,2,6,6-pentamethylpiperidyl)-sebacate,n-butyl-3,5-di-tert.butyl-4-hydroxybenzyl malonic acidbis-(1,2,2,6,6-pentamethylpiperidyl)ester, condensation product of1-hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinicacid, condensation product ofN,N'-(2,2,6,6-tetramethylpiperidyl)-hexamethylenediamine and4-tert.octylamino-2,6-dichloro-1,3,5-s-triazine,tris(2,2,6,6-tetramethylpiperidyl)-nitrilotriacetate,tetrakis-(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarbonicacid, 1,1'(1,2-ethanediyl)-bis-(3,3,5,5-tetramethylpiperazinone).

2.7. Oxalic acid diamides, for example, 4,4'-di-octyloxyoxanilide,2,2'-di-octyloxy-5,5'-di-tert.butyl-oxanilide,2,2'-di-dodecyloxy-5,5'-di-tert.butyl-oxanilide,2-ethoxy-2'-ethyl-oxanilide, N,N'-bis (3-dimethylaminopropyl)oxalamide,2-ethoxy-5-tert.butyl-2'-ethyloxanilide and its mixture with2-ethoxy-2'-ethyl-5,4'-di-tert.butyloxanilide and mixtures of ortho- andpara-methoxy-as well as of o- and p-ethoxy-disubstituted oxanilides.

3. Metal deactivators, for example, N,N'-diphenyloxalic acid diamide,N-salicylal-N'-salicyloylhydrazine, N,N'-bis-salicyloylhydrazine,N,N'-bis-(3,5-di-tert.butyl-4-hydroxyphenylpropionyl)-hydrazine,3-salicyloylamino-1,2,4-triazole, bis-benzylidene-oxalic aciddihydrazide.

4. Phosphites and phosphonites, for example, triphenyl phosphite,diphenylalkyl phosphites, phenyldialkyl phosphites,tri-(nonylphenyl)phosphite, trilauryl phosphite, trioctadecyl phosphite,di-stearyl-pentaerythrit diphosphite, tris-(2,4-di-tert.butylphenyl)phosphite, di-isodecylpentaerythritol diphosphite,di-(2,4-di-tert.butylphenyl)pentaerythritol diphosphite,tristearylsorbitol triphosphite,tetrakis-(2,4-di-tert.butylphenyl)-4,4'-diphenylylenediphosphonite.

5. Compounds which destroy peroxide, for example, esters ofβ-thiodipropionic acid, for example the lauryl, stearyl, myristyl ortridecyl esters, mercapto-benzimidazole or the zinc salt of2-mercaptobenzimidazole, zinc-dibutyl-dithiocarbamate,dioctadecyldisulfide,pentaerythritol-tetrakis(β-dodecylmercapto)-propionate.

6. Polyamide stabilizers, for example copper salts in combination withiodides and/or phosphorus compounds and salts of divalent manganese.

7. Basic co-stabilizers, for example, melamine, polyvinylpyrrolidone,dicyandiamide, triallyl cyanurate, urea derivatives, hydrazinederivatives, amines, polyamides, polyurethanes, alkali metal salts andalkaline earth metal salts of higher fatty acids for example Castearate, Zn stearate, Mg stearate, Na ricinoleate and K palmitate,antimony pyrocatecholate or zinc pyrocatecholate.

8. Nucleating agents, for example, 4-tert.butyl-benzoic acid, adipicacid, diphenylacetic acid.

9. Fillers and reinforcing agents, for example, calcium carbonate,silicates, glass fibers, asbestos, talc, kaolin, mica, barium sulfate,metal oxides and hydroxides, carbon black, graphite.

10. Other additives, for example, plasticizers, lubricants, emulsifiers,pigments, optical brighteners, flameproofing agents, anti-static agents,blowing agents and thiosynergists such as dilaurylthiodipropionate ordistearylthiodipropionate.

While the instant compounds can be beneficially used as stabilizers fora variety of substrates, particularly the polyolefins, both alone and inconjunction with other coadditives, the introduction of the instantcompounds into polyolefins, optionally containing various alkali metal,alkaline earth metal and aluminum salts of higher fatty acids (seeAdditive #7 hereinabove), with hindered phenolic antioxidants results inenhanced and particularly salubrious protection to such substrates interms of reducing color formation stemming from the presence of thephenols. Such phenolic antioxidants include n-octadecyl3,5-di-tert-butyl-4-hydroxyhydrocinnamate, neopentanetetrayltetrakis-(3,5-di-tert-butyl-4-hydroxyl-hydrocinnamate), di-n-octadecyl3,5-di-tert-butyl-4-hydroxybenzyl-phosphonate,1,3,5-tris(3,5-di-tert-butyl-4-hydroxy-benzyl)isocyanurate,thiodiethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate),1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl)benzene,3,6-di-oxaoctamethylenebis(3-methyl-5-tert-butyl-4-hydroxyhydrocinnamate),2,6-di-tert-butyl-p-cresol,2,2'-ethylidene-bis(4,6-di-tert-butylphenol),1,3,5-tris(2,6-di-methyl-4-tert-butyl-3-hydroxybenzyl)isocyanurate,1,1,3-tris-(2-methyl-4-hydroxy-5-tert-butylphenyl)butane,1,3,5-tris-[2-(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyloxy)-ethyl]-isocyanurate,3,5-di-(3,5-di-tert-butyl-4-hydroxybenzyl)-mesitol, hexamethylenebis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate),1-(3,5-di-tert-butyl-4-hydroxyanilino)-3,5-di(octylthio)-s-triazine,N,N'-hexamethylene-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamamide),calcium bis(ethyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate),ethylene bis[3,3-di(3-tert-butyl-4-hydroxyphenyl)butyrate], octyl3,5-di-tert-butyl-4-hydroxybenzylmercaptoacetate,bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyl)hydrazide, andN,N'-bis-[2-(3,5-tert-butyl-4-hydroxyhydroxo-cinnamoyloxy)ethyl]-oxamide,and preferably neopentanetetrayltetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), n-octadecyl3,5-di-tert-butyl-4-hydroxyhydrocinnamate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene,1,3,5-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate,2,6-di-tert-butyl-p-cresol or2,2'-ethylidene-bis(4,6-di-tert-butylphenol).

Likewise, the instant compounds prevent color formation when hinderedamine light stabilizers are present, such hindered amines includingbis(1,2,2,6,6-pentamethyl-4-piperidyl)-2-n-butyl-2-(3,5-di-tert-butyl-4-hydroxybenzyl)malonate; bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate;dimethylsuccinate polymer with4-hydroxy-2,2,6,6-tetramethyl-1-piperidinethanol; and polymer of2,4-dichloro-6-octylamino-s-triazine withN'-(2,2,6,6-tetramethyl-4-piperidyl)hexamethylene diamine.

The following examples illustrate the embodiments of this invention. Inthese examples, all parts given are by weight unless otherwisespecified.

EXAMPLE I Di-n-butyl-2-(N,N-dibenzylaminoxy)succinate

A solution of 10.0 g of N,N-dibenzylhydroxylamine, 10.7 g ofdi-n-butylmaleate and 0.53 g of potassium-tert-butoxide in 100 ml oftetrahydrofuran is heated under reflux for 48 hours. The crude reactionmixture is concentrated under reduced pressure and the residue ispartitioned between water and methylene chloride. The organic layer iswashed with water, brine, dried (MgSO₄) and then evaporated underreduced pressure. Purification by liquid chromatography affords thetitle compound as a colorless oil.

Anal. Calcd. for C₂₆ H₃₅ NO₅ : C, 70.7; H, 8.0; N, 3.2. Found: C, 70.5;H, 8.2; N, 3.0.

EXAMPLE II Di-2-ethylhexyl-2-(N,N-dibenzylaminoxy)succinate

A solution of 13.67 g of N,N-dibenzylhydroxylamine and 21.82 g ofdi-(2-ethylhexyl)maleate in 50 ml of tetrahydrofuran is heated underreflux for 48 hours. The solvent is removed under reduced pressure andthe residue is chromatographed to afford the title compound as a clearcolorless liquid.

Anal. Calcd. for C₃₄ H₅₁ NO₅ : C, 73.7; H, 9.3; N, 2.5. Found: C, 72.6;H, 9.3; N, 2.2.

EXAMPLE III Di-2-ethylhexyl-2-(N,N-diethylaminoxy)succinate

A solution of 10.7 g of diethylhydroxylamine and 34.1 g ofdi(2-ethylhexyl)maleate in 100 ml of diglyme is heated under reflux for32 hours. The solvent is removed under pressure and the residue ispurified by liquid chromatography to afford the title compound as aclear colorless liquid.

Anal. Calcd. for C₂₄ H₄₇ NO₅ : C, 67.1; H, 11.0; N, 3.3. Found: C, 67.9;H, 11.3; N, 2.9.

EXAMPLE IV

When the procedure of Example I is repeated using di-n-dodecyl maleateor di-n-octadecyl maleate in place of the di-n-butyl maleate, thecorresponding succinates are isolated.

EXAMPLE V

When the procedure of Example I is repeated usingdioctadecylhydroxylamine and di-n-octadecyl maleate or di-2-ethylhexylmaleate, the corresponding succinates are isolated.

EXAMPLE VI Processing of Polypropylene

    ______________________________________                                        Base Formulation                                                              ______________________________________                                        Polypropylene*        100    parts                                            Calcium Stearate      0.10   part                                             ______________________________________                                         *Profax 6501 from Himont USA                                             

The indicated stabilizers are solvent blended into polypropylene assolutions in methylene chloride and after removal of solvent byevaporation at reduced pressure, the resin is extruded using thefollowing extruder conditions.

    ______________________________________                                                       Temperature (°C.)                                       ______________________________________                                        Cylinder #1          232                                                      Cylinder #2          246                                                      Cylinder #3          260                                                      Gate #1              260                                                      Gate #2              260                                                      Gate #3              260                                                      RPM           100                                                             ______________________________________                                    

During extrusion, the internal extruder pressure is determined using apressure transducer. After each of the first, third and fifthextrusions, resin pellets are compression molded into 125 mil(3.2 mm)thick plaques at 193° C. and specimen yellowness index (Y.I.) determinedaccording to ASTM D1925-63T.

The melt fow rate (MFR) is determined by ASTM method 1238 condition L.The melt flow rate varies inversely as the transducer pressure and bothare a measure of the molecular weight for a specific type of polymer.The results are shown in the following table.

    ______________________________________                                                  Extrusion Temperature                                                                        Melt Flow Rate                                                 260° C. YI Color                                                                      After Extrusion                                                After Extrusion                                                                              (g/10 Min)                                           Additives   1       3        5     1     5                                    ______________________________________                                        Base Resin  1.5     2.2      2.9   9.2   86.7                                 0.1% Antioxidant A                                                                        6.9     8.2      9.6   4.7   9.7                                  0.1% Antioxidant A                                                                        2.3     5.0      8.1   4.1   8.5                                  + 0.05% Ex. II                                                                0.1% Antioxidant A                                                                        2.4     4.6      5.7   3.4   5.1                                  + 0.05% Ex. III                                                               ______________________________________                                         Antioxidant A  Neopentyl tetrakis                                             [3(3',5di-tert-butyl-4hydroxyphenyl)propanoate]?                         

These data thus indicate the effective color improving and processstabilization characteritics of the instant compounds.

Summarizing, it is seen that this invention provides novel compoundswhich exhibit effective stabilization and color improving activity.Variations may be made in proportions, procedures and materials withoutdeparting from the scope of the invention as defined by the followingclaims.

What is claimed is:
 1. A compound of the formula ##STR3## wherein R¹ andR² are independently alkyl of 1 to 36 carbon atoms, cycloalkyl of 5 to12 carbon atoms, aralkyl of 7 to 9 carbon atoms or said aralkylsubstituted by alkyl of 1 to 36 carbon atoms; andR³ and R⁴ areindependently hydrogen, an alkali metal, alkyl of 1 to 36 carbon atoms,phenyl or phenyl substituted by alkyl of 1 to 12 carbon atoms.
 2. Thecompound of claim 1, wherein R¹ and R² are independently straight-chainor branched alkyl of 1 to 18 carbon atoms, cyclopentyl, cyclohexyl,benzyl, α-methylbenzyl, α,α-dimethylbenzyl or cumyl benzyl.
 3. Thecompound of claim 2, wherein R¹ and R² are benzyl.
 4. The compound ofclaim 1, wherein R³ and R⁴ are independently straight-chain or branchedalkyl of 1 to 18 carbon atoms. 5.Di-n-butyl-2-(N,N-dibenzylaminoxy)succinate according to claim
 3. 6.Di-2-ethylhexyl-2-(N,N-dibenzylaminoxy)succinate according to claim 3.7. Di-2-ethylhexyl-2-(N,N-diethylaminoxy)succinate according to claim 2.8. Di-2-ethylhexyl-2-(N,N-dioctadecylaminoxy)succinate according toclaim
 2. 9. Di-n-octadecyl-(N,N-dioctadecylaminoxy)succinate accordingto claim
 2. 10. A composition of matter comprising an organic materialsubject to oxidative, thermal and actinic degradation stabilized with aneffective stabilizing amount of a compound of claim
 1. 11. Thecomposition of claim 10, wherein the organic material is a syntheticpolymer.
 12. The composition of claim 11, wherein the synthetic polymeris a polyolefin homopolymer or copolymer.
 13. The composition of claim12 which also contains a metal salt of a higher fatty acid.
 14. Thecomposition of claim 10, which also contains a phenolic antioxidant. 15.The composition of claim 13 which also contains a phenolic antioxidant.16. The composition of claim 14, wherein said phenolic antioxidant isselected from the group consisting of n-octadecyl3,5-di-tert-butyl-4-hydroxyhydrocinnamate,neopentanetetrayltetrakis-(3,5-di-tert-butyl-4-hydroxylhydrocinnamate),di-n-octadecyl 3,5-di-tert-butyl-4-hydroxy-benzyl-phosphonate,1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate,thiodiethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxy-benzyl) benzene,3,6-di-oxaocta-methylenebis(3-methyl-5-tert-butyl-4-hydroxyhydro-cinnamate),2,6-di-tert-butyl-p-cresol,2,2'-ethylidene-bis(4,6-di-tert-butylphenol),1,3,5-tris(2,6-di-methyl-4-tert-butyl-3-hydroxybenzyl)isocyanurate,1,1,3-tris-(2-methyl-4-hydroxy-5-tert-butyl-phenyl)butane,1,3,5-tris-[2-(3,5-di-tert-butyl-4-hydroxyhydro-cinnamoyl-oxy)-ethyl]-isocyanurate,3,5-di-(3,5-di-tert-butyl-4-hydroxybenzyl)-mesitol, hexamethylenebis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate),1-(3,5-di-tert-butyl-4-hydroxyanilino)-3,5-di(octylthio)-s-triazine,N,N'-hexamethylene-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamamide),calcium bis(ethyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate),ethylene bis[3,3-di(3-tert-butyl-4-hydroxyphenyl)butyrate], octyl3,5-di-tert-butyl-4-hydroxybenzylmercaptoacetate,bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyl)hydrazide, andN,N'-bis[2-(3,5-tert-butyl-4-hydroxyhydroxo-cinnamoyloxy)ethyl]-oxamide.17. The composition of claim 16, wherein said phenolic antioxidant isneopentanetetrayl tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate),n-octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate,1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene,1,3,5-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate,2,6-di-tert-butyl-p-cresol or2,2'-ethylidene-bis(4,6-di-tert-butylphenol).
 18. A method forstabilizing an organic material against oxidative, thermal and actinicdegradation which comprises incorporating into said organic material aneffective stabilizing amount of a compound of claim 1.